Efficient Stress and Failure Analysis of Bolted Joints for Composite Laminates

lted joints are widely used to connect safety relevant parts in the aeronautical industry and require precise stress analysis tools. If the joint has a fully symmetric setup with respect to the midplane a plane problem modelling is applicable. Focus of this paper is the analytical stress field determination and load transfer modelling of a finite dimensions bolted joint with isotropic material using the Airy stress function enabling cost-efficient computation. The load is introduced by sinusoidal radial stresses at the hole boundary idealising the bolt contact. It is led through the net section plane, in which crack initiation and propagation have to be avoided. This requires accurately calculated net section stresses carrying the whole load. To reach this aim the stress boundary conditions in load direction at the straight free edges must be fulfilled. To solve this first boundary value problem the stress field describing the load introduction is determined while neglecting the stress free boundary conditions at the straight edges. Then auxiliary functions are superimposed cancelling non-zero tractions in load direction at the straight edges and thus providing a physical force flux. Since traction boundary conditions perpendicular to the load direction are not covered inaccuracies in the stress solution may arise. Their criticality will be assessed by conducting a failure analysis in which predictions derived using the stresses of the present calculus are compared to literature values.